Having worked for a Real Estate webhost who provided email campaigns as a service, we got those all the time. Someone who wasn't subscribed in the system, but w

Having worked for a Real Estate webhost who provided email campaigns as a service, we got those all the time. Someone who wasn't subscribed in the system, but was receiving our spam nonetheless. These were usually due to an email distribution list being subscribed and that person being on that DL. Unfortunately some of these were distribution lists of distribution lists, so we couldn't see the original DL address to unsubscribe it, or help at all.